Abstract : NOT all groups that the United States government classifies as terrorist organizations are equally bad or dangerous, and not all information conveyed to them that is based on political, academic or scientific expertise risks harming our national security. Unfortunately, the Supreme Court, which last week upheld a law banning the provision of -material support- to foreign terrorist groups, doesn-t seem to consider those facts relevant

The two of us are social scientists who study and interact with violent groups in order to find ways out of intractable conflicts. In the course of this work and in our discussions with decision makers in the Middle East and elsewhere we have seen how informal meetings and exchanges of knowledge have borne fruit. It-s not that religious, academic or scientific credentials automatically convey trust, but when combined with a personal commitment to peace, they often carry weight beyond mere opinion or desire

In our own work on groups categorized as terrorist organizations, we have detected significant differences in their attitudes and actions. For example, in our recent interactions with the leader of the Palestinian militant group Islamic Jihad Ramadan Shallah which we immediately reported to the State Department, as he is on the F.B.I.-s -most wanted- list, we were faced with an adamant refusal to ever recognize Israel or move toward a two-state solution. Yet when we talked to Khaled Meshal, the leader of Hamas considered a terrorist group by the State Department, he said that his movement could imagine a two-state -peace- he used the term -salaam,- not just the usual -hudna,- which signifies only an armistice. In our time with Mr. Meshal-s group, we were also able to confirm something that Saudi and Israeli intelligence officers had told us: Hamas has fought to keep Al Qaeda out of its field of influence, and has no demonstrated interest in global jihad. Whether or not the differences among Al Qaeda, Islamic Jihad, Hamas and other violent groups are fundamental, rather than temporary or tactical, is something only further exploration will reveal. But to assume that it is invariably wrong to engage any of these groups is a grave mistake